U.S. patent application number 11/527617 was filed with the patent office on 2007-04-05 for steering shaft supporting structure of vehicle.
This patent application is currently assigned to HONDA MOTOR CO., LTD.. Invention is credited to Kihoko Kaita, Yotaro Mori, Megumu Okada, Hiroaki Tomita, Takeshi Wakabayashi, Keita Yagi.
Application Number | 20070074928 11/527617 |
Document ID | / |
Family ID | 37650316 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070074928 |
Kind Code |
A1 |
Okada; Megumu ; et
al. |
April 5, 2007 |
Steering shaft supporting structure of vehicle
Abstract
To make an electrically-operated power steering unit less
susceptible to influence of change in a positional relationship
between supporting sections respectively at the two ends of the
electrically-operated power steering unit. A gear case included in
a electrically-operated power steering unit is attached to the
lower section of a vehicle body frame, and the lower end portion of
a steering shaft is rotatably supported by a housing annexed to the
gear case with an upper bearing interposed in between, in a vehicle
in which an input shaft provided to the electrically-operated power
steering unit is linked to the lower end portion of the steering
shaft, and in which an output shaft provided to the
electrically-operated power steering unit is rotatably supported by
the lower section of a vehicle body.
Inventors: |
Okada; Megumu; (Saitama,
JP) ; Yagi; Keita; (Saitama, JP) ; Mori;
Yotaro; (Saitama, JP) ; Wakabayashi; Takeshi;
(Saitama, JP) ; Kaita; Kihoko; (Saitama, JP)
; Tomita; Hiroaki; (Saitama, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
HONDA MOTOR CO., LTD.
|
Family ID: |
37650316 |
Appl. No.: |
11/527617 |
Filed: |
September 27, 2006 |
Current U.S.
Class: |
180/444 |
Current CPC
Class: |
B62D 5/04 20130101; B62K
5/08 20130101; B62K 5/01 20130101 |
Class at
Publication: |
180/444 |
International
Class: |
B62D 5/04 20060101
B62D005/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 2005 |
JP |
2005-288031 |
Claims
1. A steering shaft supporting structure for a vehicle wherein a
steering shaft is rotatably supported by an upper section of a
vehicle body frame and a handlebar is attached to an upper end of
this steering shaft with an input shaft provided to an
electrically-operated power steering unit being linked to a lower
end portion of the steering shaft and an output shaft provided to
the electrically-operated power steering unit being rotatably
supported by a lower section of the vehicle body frame, the
steering shaft supporting structure comprising: a gear case
included in the electrically-operated power steering unit, said
gear case being attached to the lower section of a vehicle body
frame, and the lower end portion of the steering shaft being
rotatably supported by a housing annexed to the gear case with a
bearing interposed in between.
2. The steering shaft supporting structure of the vehicle according
to claim 1, wherein a lower section of the steering shaft is
provided with a handlebar stopper for limiting an angle at which
this steering shaft rotates to a predetermined angle, and a part of
the steering shaft in a vicinity of the handlebar stopper is
attached to the housing with the bearing interposed in between.
3. The steering shaft supporting structure of the vehicle according
to claim 1, wherein a lower end portion of the steering shaft and
the input shaft are linked to each other, and concurrently the
steering shaft and the input shaft are configured to be capable of
being displaced relative to each other in axial directions
thereof.
4. The steering shaft supporting structure of the vehicle according
to claim 2, wherein a lower end portion of the steering shaft and
the input shaft are linked to each other, and concurrently the
steering shaft and the input shaft are configured to be capable of
being displaced relative to each other in axial directions
thereof.
5. The steering shaft supporting structure of the vehicle according
to claim 1, wherein the bearing is configured to be of a double-row
type.
6. The steering shaft supporting structure of the vehicle according
to claim 2, wherein the bearing is configured to be of a double-row
type.
7. The steering shaft supporting structure of the vehicle according
to claim 3, wherein the bearing is configured to be of a double-row
type.
8. The steering shaft supporting structure of the vehicle according
to claim 1, wherein the steering shaft is divided into separate
units which are an upper shaft near the handlebar and an lower
shaft including the handlebar stopper, one linkage portion where
the upper shaft and the lower shaft are linked to each other is
formed in the shape of a shaft, the other linkage portion where the
upper shaft and the lower shaft are linked with each other is
formed in the shape of a hole, and concurrently an expanding slot
is provided in an interstice between an outer circumferential
surface of the linkage portion and an inner circumferential surface
of the hole, and one of the linkage portions is fitted into the
other of the linkage portions above the bearing, and the linkage
portions are fastened to each other.
9. The steering shaft supporting structure of the vehicle according
to claim 2, wherein the steering shaft is divided into separate
units which are an upper shaft near the handlebar and an lower
shaft including the handlebar stopper, one linkage portion where
the upper shaft and the lower shaft are linked to each other is
formed in the shape of a shaft, the other linkage portion where the
upper shaft and the lower shaft are linked with each other is
formed in the shape of a hole, and concurrently an expanding slot
is provided in an interstice between an outer circumferential
surface of the linkage portion and an inner circumferential surface
of the hole, and one of the linkage portions is fitted into the
other of the linkage portions above the bearing, and the linkage
portions are fastened to each other.
10. The steering shaft supporting structure of the vehicle
according to claim 3, wherein the steering shaft is divided into
separate units which are an upper shaft near the handlebar and an
lower shaft including the handlebar stopper, one linkage portion
where the upper shaft and the lower shaft are linked to each other
is formed in the shape of a shaft, the other linkage portion where
the upper shaft and the lower shaft are linked with each other is
formed in the shape of a hole, and concurrently an expanding slot
is provided in an interstice between an outer circumferential
surface of the linkage portion and an inner circumferential surface
of the hole, and one of the linkage portions is fitted into the
other of the linkage portions above the bearing, and the linkage
portions are fastened to each other.
11. The steering shaft supporting structure of the vehicle
according to claim 4, wherein the steering shaft is divided into
separate units which are an upper shaft near the handlebar and an
lower shaft including the handlebar stopper, one linkage portion
where the upper shaft and the lower shaft are linked to each other
is formed in the shape of a shaft, the other linkage portion where
the upper shaft and the lower shaft are linked with each other is
formed in the shape of a hole, and concurrently an expanding slot
is provided in an interstice between an outer circumferential
surface of the linkage portion and an inner circumferential surface
of the hole, and one of the linkage portions is fitted into the
other of the linkage portions above the bearing, and the linkage
portions are fastened to each other.
12. The steering shaft supporting structure of the vehicle
according to claim 8, wherein a portion for positioning the bearing
and a portion for positioning the upper shaft are formed in the
lower shaft.
13. The steering shaft supporting structure of the vehicle
according to claim 9, wherein a portion for positioning the bearing
and a portion for positioning the upper shaft are formed in the
lower shaft.
14. The steering shaft supporting structure of the vehicle
according to claim 10, wherein a portion for positioning the
bearing and a portion for positioning the upper shaft are formed in
the lower shaft.
15. The steering shaft supporting structure of the vehicle
according to claim 11, wherein a portion for positioning the
bearing and a portion for positioning the upper shaft are formed in
the lower shaft.
16. The steering shaft supporting structure of the vehicle
according to claim 2, wherein a second handlebar stopper is
provided to a lower section of the electrically-operated power
steering unit, and the handlebar stopper is configured to start to
operate before the second handlebar stopper operates, when
rightward and leftward steering is performed with the
handlebar.
17. The steering shaft supporting structure of the vehicle
according to claim 3, wherein a second handlebar stopper is
provided to a lower section of the electrically-operated power
steering unit, and the handlebar stopper is configured to start to
operate before the second handlebar stopper operates, when
rightward and leftward steering is performed with the
handlebar.
18. The steering shaft supporting structure of the vehicle
according to claim 4, wherein a second handlebar stopper is
provided to a lower section of the electrically-operated power
steering unit, and the handlebar stopper is configured to start to
operate before the second handlebar stopper operates, when
rightward and leftward steering is performed with the
handlebar.
19. The steering shaft supporting structure of the vehicle
according to claim 5, wherein a second handlebar stopper is
provided to a lower section of the electrically-operated power
steering unit, and the handlebar stopper is configured to start to
operate before the second handlebar stopper operates, when
rightward and leftward steering is performed with the
handlebar.
20. The steering shaft supporting structure of the vehicle
according to claim 6, wherein a second handlebar stopper is
provided to a lower section of the electrically-operated power
steering unit, and the handlebar stopper is configured to start to
operate before the second handlebar stopper operates, when
rightward and leftward steering is performed with the
handlebar.
21. The steering shaft supporting structure of the vehicle
according to claim 1, wherein an opening is provided to a rear
surface of the housing, and a conductor to be connected to the
electrically-operated power steering unit is configured to pass
through the opening.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 USC 119 to
Japanese Patent Application No. 2005-288031 filed on Sep. 30, 2005
the entire contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to modification of a steering
shaft supporting structure of a vehicle.
[0004] 2. Description of Background Art
[0005] A structure for supporting an input shaft and an output
shaft of a power steering system respectively with different
constituent members of a vehicle body frame has been heretofore
known as a conventional type of a steering shaft supporting
structure of a vehicle. See, Japanese Patent Laid-open Official
Gazette No. 2004-23101.
[0006] The following configuration is described in FIG. 4 of
Japanese Patent Laid-open Official Gazette No. 2004-23101. In this
configuration, an upper shaft 50a of a steering shaft 50 is
rotatably attached to an upper pipe 18 constituting a vehicle body
frame by use of a shaft supporting member 52, an end of a lower
shaft 50b provided to an electrically-operated power steering
system is linked to the upper shaft 50a by use of a universal joint
51, and the other end of the lower shaft 50b is rotatably attached
to a lower bracket 54 provided to a front cross pipe 23 by use of a
gear case 55.
[0007] The upper shaft 50a and the lower shaft 50b constituting the
steering shaft 50 are supported respectively by different members
which are the upper pipe 18 and the front cross pipe 23. As a
result, the distance between, and a positional relation between,
the shaft supporting member 52 near the upper shaft 50a and the
lower bracket 54 near the lower shaft 50b vary, for example, due to
inaccuracy in manufacturing the vehicle body frame, and due to
change in shape of the vehicle body frame which is caused when an
external force works on the vehicle body frame. If this variation
becomes larger, the universal joint 51 is not capable of
accommodating this variation. Accordingly, the supporting of the
electrically-operated power steering system becomes susceptible to
the variation.
SUMMARY AND OBJECTS OF THE INVENTION
[0008] An object of an embodiment of the present invention to make
an electrically-operated power steering unit less susceptible to
influence of a change in a positional relationship between
supporting sections respectively at the two ends of the
electrically-operated power steering unit.
[0009] According to an embodiment of the present invention, a gear
case of an electrically-operated power steering unit is attached to
the lower section of a vehicle body frame with the lower end
portion of a steering shaft being rotatably supported by a housing
annexed to the gear case with a bearing interposed in between. A
steering shaft is rotatably supported by the upper section of the
vehicle body frame with a handlebar being attached to the upper end
of this steering shaft. An input shaft is provided to the
electrically-operated power steering unit that is linked to the
lower end portion of the steering shaft. An output shaft is
provided to the electrically-operated power steering unit that is
rotatably supported by the lower section of the vehicle body
frame.
[0010] As the working effect of supporting the
electrically-operated power steering unit, the input shaft of the
electrically-operated power steering unit is supported by the lower
section of the vehicle body frame by use of the housing and the
gear case, and the output shaft of the electrically-operated power
steering unit is also supported by the lower section of the vehicle
body frame.
[0011] Both the input shaft and the output shaft of the
electrically-operated power steering unit are supported by the
lower section of the same vehicle body frame in this manner. For
this reason, the electrically-operated power steering unit is less
susceptible to an influence relating to an inaccuracy in
manufacturing the vehicle body frame, a change in shape of the
vehicle body frame, and the like.
[0012] According to an embodiment of the present invention, a lower
section of the steering shaft is provided with a handlebar stopper
for limiting an angle at which this steering shaft rotates to a
predetermined angle. In addition, a part of the steering shaft in a
vicinity of this handlebar stopper is attached to the housing with
the bearing interposed in between.
[0013] As a working effect of the handlebar stopper, the handlebar
stopper limits the angle at which the steering shaft rotates to the
predetermined angle. For example, this prevents a torsion bar from
detecting a steering torque from being twisted beyond the
predetermined angle, the torsion bar being included in the
electrically-operated power steering unit.
[0014] In addition, the part of the steering shaft in the vicinity
of the handlebar stopper is attached to the housing with the
bearing interposed in between. This attachment makes it possible to
receive a torque, which is caused when the handlebar stopper is
operated, by use of a rigid bearing supporting unit.
[0015] According to an embodiment of the present invention, the
lower end portion of the steering shaft and the input shaft are
linked to each other, and concurrently that the steering shaft and
the input shaft are configured to be capable of being displaced
relative to each other in an axial directions thereof.
[0016] As a working effect of linking the steering shaft and the
input shaft with each other, when an external force works on the
steering shaft due to an inaccuracy in manufacturing the vehicle
body frame, an inaccuracy in assemblage of the vehicle body frame,
and a change in a shape of the vehicle body frame, the steering
shaft and the input shaft are displaced relative to each other in
the axial directions. Thereby, a thrust force is less likely to
work on the input shaft.
[0017] According to an embodiment of the present invention, the
bearing is configured to be of a double-row type.
[0018] As a working effect of the bearing, the withstand load of
the bearing increases because of the use of the bearing of the
double-row type.
[0019] According to an embodiment of the present invention, the
steering shaft is divided into separate units which are an upper
shaft near the handlebar and an lower shaft including the handlebar
stopper. One linkage portion, where the upper shaft and the lower
shaft are linked to each other, is formed in the shape of a shaft.
The other linkage portion where the upper shaft and the lower shaft
are linked to each other is formed in the shape of a hole.
Concurrently an expanding slot is provided to an interstice between
an outer circumferential surface of this linkage portion and an
inner circumferential surface of the hole with one of the linkage
portions being fitted into the other of the linkage portions above
the bearing, and the linkage portions are fastened to each
other.
[0020] As a working effect of the linkage structure concerning the
steering shaft, one of the linkage portions where the upper shaft
and the lower shaft are linked to each other and the other of the
linkage portions are fitted into each other, the former linkage
portion being formed in the shape of the shaft, and the latter
linkage portion being formed in the shape of the hole. Thus, one of
the linkage portions is fastened to the other of the linkage
portions. This makes it possible to link the upper shaft and the
lower shaft to each other easily and securely.
[0021] According to an embodiment of the present invention, a
portion for positioning the bearing and a portion for positioning
the upper shaft are formed in the lower shaft.
[0022] As a working effect of the lower shaft, the formation of the
portion for positioning the bearing and the portion for positioning
the upper shaft in the lower shaft, for example, makes it possible
to position the bearing in the housing, to position the lower shaft
in the bearing, and to position the upper shaft in the lower
shaft.
[0023] According to an embodiment of the present invention, a
second handlebar stopper is provided to a lower section of the
electrically-operated power steering unit, and that the handlebar
stopper is configured to start to operate before the second
handlebar stopper operates, when rightward and leftward steering is
performed with the handlebar.
[0024] As a working effect of the handlebar stopper and the second
handlebar stopper, in a case where the input shaft and the output
shaft are linked to each other, for example, by use of a torsion
bar for detecting the steering torque, no load works on the torsion
bar. This is because, when the handlebar is steered rightward and
leftward, the handlebar stopper operates first, and thus the
rotation is not transmitted from the input shaft to the output
shaft.
[0025] In the case of the structure in which, for example, the
second handlebar stopper operates prior to the handlebar stopper,
the input shaft up to the output shaft are twisted until the
handlebar stopper starts to operate, even after the second
handlebar stopper operates. As a result, there are some cases where
a large load works on the torsion bar.
[0026] According to an embodiment of the present invention, an
opening is provided to a rear wall of the housing, and a conductor
to be connected to the electrically-operated power steering unit is
configured to pass through the opening.
[0027] As a working effect of the opening in the housing, the
provision of the opening to the rear surface of the housing makes
flying gravel, rain water, dust and the like less likely to enter
the housing from the front of the vehicle. In addition, the causing
of the conductor to pass through the opening makes it easy to
manage the conductor, the conductor being connected to the
electrically-operated power steering unit.
[0028] According to an embodiment of the present invention, the
gear case included in the electrically-operated power steering unit
is attached to the lower section of the vehicle body frame, and the
lower end portion of the steering shaft is rotatably supported by
the housing annexed to the gear case with the bearing interposed in
between. By this, both of the input shaft and the output shaft of
the electrically-operated power steering unit are supported by the
lower section of the vehicle body frame. Consequently, in a case
where the electrically-operated power steering unit is supported by
the vehicle body frame, this support makes the
electrically-operated power steering unit less likely to be
susceptible to the influence of an inaccuracy in manufacturing the
vehicle body frame, a change in shape thereof and the like.
[0029] According to an embodiment of the present invention, the
lower section of the steering shaft is provided with the handlebar
stopper for limiting the angle at which this steering shaft rotates
to the predetermined angle, and the part of the steering shaft in
the vicinity of this handlebar stopper is attached to the housing
with the bearing interposed in between. By the handlebar stopper,
it is made possible, for example, to prevent the torsion bar for
detecting the steering torque from being twisted beyond the
predetermined angle, the torsion bar being included in the
electrically-operated power steering unit.
[0030] In addition, the attaching of the part of the steering shaft
in the vicinity of the handlebar stopper to the housing with the
bearing interposed in between makes it possible to receive a
torque, which is generated when the handlebar stopper operates, by
a rigid bearing supporting unit.
[0031] According to an embodiment of the present invention, the
lower end portion of the steering shaft and the input shaft are
linked to each other, and concurrently the steering shaft and the
input shaft are configured to be capable of being displaced
relative to each other in the axial directions. This makes it
possible to make a thrust force less likely to work on the input
shaft, and to accordingly protect the electrically-operated power
steering unit, when an external force works on the steering shaft
because of an inaccuracy in manufacturing, and assemblage into, the
vehicle body frame as well as change in the shape thereof.
[0032] According to an embodiment of the present invention, the
bearing is configured to be of the double-row type. This makes it
possible to enlarge bearing load (withstand load of the bearing)
which the bearing is capable of supporting, and to further inhibit
the lower end portion of the steering shaft from tilting. As a
result, tilting load put on the steering shaft is less likely to
work on the input shaft.
[0033] According to an embodiment of the present invention, the
steering shaft is divided into the separate units which are the
upper shaft near the handlebar and the lower shaft including the
handlebar stopper with one linkage portion where the upper shaft
and the lower shaft are linked to each other being formed in the
shape of a shaft. The other linkage portion where the upper shaft
and the lower shaft are linked to each other is formed in the shape
of a hole, and concurrently the expanding slot is provided in the
interstice between the outer circumferential surface of this
linkage portion and the inner circumferential surface of the hole.
One of the linkage portions is fitted into the other of the linkage
portions above the bearing, and the linkage portions are fastened
to each other. This makes it possible to link the upper shaft and
the lower shaft to each other easily and securely.
[0034] According to an embodiment of the present invention, the
portion for positioning the bearing and the portion for positioning
the upper shaft are formed in the lower shaft. Thereby, for
example, the bearing is positioned in the housing, the lower shaft
is positioned in the bearing, and the upper shaft is positioned in
the lower shaft. In this manner, the assemblage can be carried out
efficiently.
[0035] According to an embodiment of the present invention, the
second handlebar stopper is provided to the lower section of the
electrically-operated power steering unit, and the handlebar
stopper is configured to start to operate before the second
handlebar stopper operates, when the leftward and rightward
steering is performed with the handlebar. As a result, in the case
where the electrically-operated power steering unit is provided
with the torsion bar for detecting the steering torque, this makes
it possible to prevent a large load from working on the torsion bar
while the handlebar is being operated.
[0036] According to an embodiment of the present invention, the
opening is provided to a rear surface of the housing, and the
conductor to be connected to the electrically-operated power
steering unit is configured to pass through the opening. This makes
it possible to make flying gravel, rain water, dust and the like
less likely to enter the housing from the front of the vehicle. In
addition, the causing of the conductor to pass through the opening
makes it possible to manage the conductor easily, the conductor
being connected to the electrically-operated power steering
unit.
[0037] Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
However, it should be understood that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various
changes and modifications within the spirit and scope of the
invention will become apparent to those skilled in the art from
this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The present invention will become more fully understood from
the detailed description given hereinbelow and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0039] FIG. 1 is a side view of a vehicle for which a steering
shaft supporting structure according to the present invention is
adopted;
[0040] FIG. 2 is a side view of a main part of the vehicle
according to the present invention;
[0041] FIG. 3 is a front view of a main part of the vehicle
according to the present invention;
[0042] FIG. 4 is a plane view of the main -part of the vehicle
according to the present invention;
[0043] FIG. 5 is a plane view of a housing according to the present
invention;
[0044] FIG. 6 is a diagram showing the housing 101 of FIG. 5 in a
direction indicated by an arrow 6;
[0045] FIG. 7 is an operational diagram showing an operation of an
upper handlebar stopper according to the present invention; and
[0046] FIG. 8 is an operational diagram showing an operation of an
lower handlebar stopper according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] Descriptions will be provided for the best mode for carrying
out the invention on the basis of the appended drawings.
Incidentally, the drawings should be looked at in a direction in
which the reference numerals read.
[0048] FIG. 1 is a side view of a vehicle for which a steering
shaft supporting structure according to the present invention is
adopted. A rough-terrain vehicle 10 as a vehicle is a
four-wheel-drive vehicle with a power unit 14 including an engine
12 and a transmission 13 being mounted in the middle section of a
vehicle body frame 11. A front-end deceleration system 17 is linked
to the front section of the transmission 13 by use of a front
propeller shaft 16. Right and left front wheels 18 and 18 are
linked to this front-end deceleration system 17 by use of a drive
shaft, which is not illustrated. A rear-end deceleration system 22
is linked to the rear section of the transmission 13 by use of a
rear propeller shaft 21. Right and left rear wheels 23 and 23 are
linked to this rear-end deceleration system 22 by use of a drive
shaft, which is not illustrated. The four-wheel-drive vehicle
includes an electrically-operated power steering unit 24 for
reducing a steering effort for steering the front wheels 18 and
18.
[0049] The vehicle body 11 includes upper main frames 31 and 32
(only reference numeral 31 denoting the upper main frame on this
side is shown), a front frame 33, right and left lower main frames
34 and 36 paired with each other (only reference numeral 34
denoting the lower main frame on this side is shown), right and
left front upper frame 41 and 42 paired with each other (only
reference numeral 41 denoting the front upper frame on this side is
shown), right and left oblique frames 43 and 44 paired with each
other (only reference numeral 43 denoting the oblique frame on this
side is shown), and left and right sub-oblique frames 46 and 47
paired with each other (only reference numeral 46 denoting the
sub-oblique frame on this side is shown). The upper main frames 31
and 32 extend forwards and backwards. The front frame 33 is linked
to the front ends respectively of these upper main frames 31 and
32, and is shaped like the letter U, which is turned upside down,
when viewed from the front of the vehicle. The lower main frames 34
and 36 are linked to the lowermost end of the front frame 33, and
concurrently are linked respectively to the middle sections
respectively of the upper main frames 31 and 32. The front upper
frames 41 and 42 are linked to the uppermost end of the front frame
33, and concurrently are linked respectively to the upper main
frames 31 and 32, for the purpose of rotatably supporting the upper
section of a steering shaft 38. A handlebar 37 is attached to the
uppermost section of the steering shaft 38. The front upper frames
41 and 42 are shaped like a parenthesis <. The oblique frames 43
and 44 are linked respectively to the lower main frames 34 and 36
in a way that the oblique frames 43 and 44 extend backwards
respectively from the front ends of the upper main frames 31 and 32
downwards to the lower main frames 34 and 36. The sub-oblique
frames 46 and 47 are linked respectively to the middle sections of
these oblique frames 43 and 44, and concurrently are linked to the
front frame 33, in a way that the sub-oblique frame 46 spans
between the middle section of the oblique frame 43 and the front
frame 33, and in a way that the sub-oblique frame 47 spans between
the middle section of the oblique frame 44 and the front frame 33.
In this way, the sub-oblique frame 46 and 47 support the lower
section of the electrically-operated power steering unit 24.
[0050] In this respect, a front carrier 55 is provided together
with a front fender 56, a fuel tank 57, a seat 58, a rear carrier
61, carburetor 62, an air cleaner 66, an exhaust pipe 68, a muffler
69, a swing arm 71, left and right rear shock absorber units 72 and
72 paired with each other (only reference numeral 72 denoting the
rear shock absorber unit on this side is shown), a body side cover
73, a rear fender 74, a step floor 75 and a skid plate 76. The
front fender 56 covers the top and the rear of the front wheel 18.
The carburetor 62 is linked to the rear section of a cylinder head
63 of the engine 12. The air cleaner 66 is linked to the carburetor
62 by use of a connecting tube 67. The exhaust pipe 68 extends from
the front section of the cylinder head 63 towards the rear section
of the vehicle. The muffler 69 is connected to the rear end of the
exhaust pipe 68. The swing arm 71 swingably supports the rear
wheels 23 and 23 respectively to the lower main frames 34 and 36.
The rear shock absorber units 72 and 72 are attached to the swing
arm 71, and concurrently are linked respectively to the upper main
frames 31 and 32, in a way that the rear shock absorber unit 72
spans between the swing arm 71 and the upper main frame 31, and in
a way that the rear shock absorber unit 72 is spanned between the
swing arm 71 and the upper main frame 32. The body side cover 73 is
disposed at the sides of the power unit 14. The rear fender 74
covers the top and the front of the rear wheel 23. The skid plate
76 covers the front lower sections respectively of the right and
left lower main frames 34 and 36, and covers the front of the lower
main frames 34 and 36.
[0051] FIG. 2 is a side view of a main part of the vehicle
according to the present invention, and shows the following
configurations. The middle section of the steering shaft 38 is
rotatably supported by the upper section of the vehicle body frame
11. An input shaft 81, included in the upper portion of the
electrically-operated power steering unit 24, is linked to the
lowermost section of the steering shaft 38. The lower section of
this electrically-operated power steering unit 24 is attached to a
lower section of the vehicle body frame 11, and an output shaft 82,
included in the lower section of the electrically-operated power
steering shaft 24, is rotatably supported by the lower section of
the vehicle body frame 11.
[0052] The steering shaft 38 is configured of an upper shaft 85 and
a lower shaft 86. The handlebar 37 (see FIG. 1) is attached to the
upper end of the upper shaft 85. The upper section of the lower
shaft 86 is linked to the lower end of the upper shaft 85 with a
serration, and the lower section of the lower shaft 86 is linked to
the input shaft 81 with a serration.
[0053] The upper shaft 85 is a member which is rotatably attached
to a steering supporting bracket 88 with an upper bearing unit 91
interposed in between. The steering supporting bracket 88 is
attached to the right and left front upper frames 41 and 42 in a
way that the steering supporting bracket 88 spans between the right
and left front upper frames 41 and 42. A female serration 85a is
formed in the lower end of the upper shaft 85. The female serration
85a is linked to a male serration 86a provided to the upper end of
the lower shaft 86. An expanding slot 85b is formed in the upper
shaft 85. The expanding slot 85b communicates with the female
serration 85a and the outer peripheral surface, and extends in the
axial direction of the upper shaft 85. Projecting portions 85c and
85d are integrally formed respectively with the two edges of this
expanding slot 85b (only reference numeral 85d denoting the
protruding portion on the back side is shown). Bolt inserting holes
85e are made respectively in the projecting portions 85c and 85d. A
bolt 92 is inserted in each of the bolt inserting holes 85e, and a
nut (not illustrated) is screwed to the extremity of the bolt 92.
Thereby, the upper end of the lower shaft 86 is fastened with the
lower end of the upper shaft 85. In addition, a positioning portion
86A is provided to the lower shaft 86 for the purpose of
positioning the upper shaft 85 by touching a tip of the upper shaft
85 to the positioning portion.
[0054] The steering supporting bracket 88 is configured of a
crossed member 93 as well as right and left boss portions 94 and 94
(only reference numeral 94 denoting the boss portion on this side
is shown). The crossed member 93 is spanned between the front upper
frames 41 and 42. The right and left boss portions 94 and 94 are
attached to this crossed member 93. A bolt 95 is screwed into each
of the boss portions 94 and 94. Thereby, the upper bearing unit 91
is fixed thereto.
[0055] The upper bearing unit 91 is configured of a bushing (not
illustrated) and a pair of holding fittings 97 and 97. The bushing
is slidably fitted to the upper shaft 85. The pair of holding
fittings 97 and 97 holds this bushing.
[0056] The lower shaft 86 includes an axle portion 86b in the lower
section thereof, and an L-shaped projecting portion 86c in the
middle section thereof. The L-shaped projecting portion 86c
projects backwards in the shape of the letter L. The lower shaft 86
is a member formed to have a female serration 86d which is linked
to a male serration 81a formed in the extremity of the input shaft
81.
[0057] A housing 101 covering over the electrically-operated power
steering unit 24 is annexed with the electrically-operated power
steering unit 24. The housing 101 is a member as follows. The lower
section of the housing 101 is attached to a gear case 102 of the
electrically-operated power steering unit 24 with a plurality of
bolts 103. The upper section of the housing 101 rotatably supports
the axle portion 86b of the lower shaft 86 with a middle-section
bearing unit 104 interposed in between.
[0058] The middle-section bearing unit 104 is configured of an
upper bearing 107, a locating snap ring 108, a sealing member 111,
a collar 112, a nut 113 and a sealing member 114. The upper bearing
107 is of a double-row type, and is fitted to a hole section 101a
and the axle portion 86b, and the hole section 101a is perforated
in the upper section of the housing 101. The locating snap ring 108
is positioned at an end of this upper bearing 107. The sealing
member 111 is caused to be adjacent to this locating snap ring 108,
and thus is fitted to an end portion of the hole section 101a. The
collar 112 is fitted to the axle portion 86b, and is touched with
the other end of the upper bearing 107. The nut 113 is screwed to a
male screw 86f in the extremity of the axle portion 86b, and
thereby the upper bearing 107 is fixed with the nut 113 while the
other end of the upper bearing 107 is being pressed against the nut
113 with the collar 112 interposed in between. The sealing member
114 is fitted to the interstice between the hole section 101a and
the collar 112. In addition, a positioning portion 86B is formed in
the axle portion 86b for the purpose of positioning the upper
bearing 107 by touching the end of the upper bearing 107 with the
positioning portion.
[0059] As described above, the lower shaft 86 of the steering shaft
38 including the lower end portion of the lower shaft 86 is
supported by the housing 101 with the upper bearing 107 interposed
in between. Along with the electrically-operated steering unit 24,
the lower shaft 86 is attached to the vehicle body frame 11. In
addition, the lower shaft 86 is linked to the upper shaft 85 of the
steering shaft 38.
[0060] The electrically-operated steering unit 24 includes the
input shaft 81 and the output shaft 82, a torque sensor unit 121
and a power assist unit 122. The torque sensor unit 121 detects a
steering torque. The power assist unit 122 generates power for
assisting the power steering. The electrically-operated power
steering unit 24 controls the power assist unit 122 with a control
unit, which is not illustrated, on the basis of the steering torque
detected by the torque sensor unit 121 and the like.
[0061] The torque sensor unit 121 includes a torsion bar 126 linked
to the input shaft 81 and the output shaft 82.
[0062] When the input shaft 81 is rotated through operating the
handlebar 37 (see FIG. 1), a relative rotational angle occurs
between the input shaft 81 and the output shaft 82, and thus the
torsion bar 126 is twisted. The steering torque is obtained by
converting this amount of twist to a torque.
[0063] The power assist unit 122 is a section configured of an
electric motor 128, a clutch (not illustrated) and a deceleration
system (not illustrated). The clutch is interposed between an
output axle of this electric motor 128 and the output shaft 82.
(The deceleration system is configured of a worm gear and a worm
wheel.)
[0064] The power steering unit 24 has the following configuration.
A part of the gear case 102 frontward of the output shaft 82 is
attached to a lower bracket 131 with a bolt 133 by use of a frontal
supporting member 132. The lower bracket 131 is shaped like a
plate, and is attached to the sub-oblique frames 46 and 47 in a way
that the lower bracket 131 spans between the sub-oblique frames 46
and 47. In addition, a part of the gear case 102 backward of the
output shaft 82 is attached to a rear supporting member 134 with
bolt 136. The rear supporting member 134 is provided to the
sub-oblique frames 46 and 47.
[0065] As described above, the electrically-operated power steering
unit 24 is a member where the lower section of the gear case 102 is
held at two locations, which are the frontal supporting member 132
at the front side and the rear supporting member 134 at the rear
side, in a way that the output shaft 82 is interposed between the
frontal supporting member 132 and the rear supporting member
134.
[0066] The control unit controls the power assist unit 122 on the
basis of the steering torque, a steering angle, a vehicle speed of
the rough terrain vehicle 10 (see FIG. 1), and the like. The
steering torque is detected by the torque sensor unit 121. The
steering angle is detected by a steering angle sensor (not
illustrated).
[0067] A lower bearing unit 140 rotatably supports the output shaft
82. The lower bearing unit 140 includes an axle supporting member
141, a lower bearing 142 and a sealing member 143. The axle
supporting member 141 is attached to the center section of the
lower bracket 131. The lower bearing 142 is a self-aligning type,
and is attached to the axle supporting member 141 for the purpose
of rotatably supporting the output shaft 82. The sealing member 143
protects this lower bearing 142 from dust and the like.
[0068] The axle supporting member 141 includes a downward
projecting portion 141a that is formed at the front side of the
vehicle. The downward projecting portion 141a projects downwards
nearly along the output shaft 82.
[0069] A center arm 147 is provided together with a female spline
147a that is formed in the center arm 147. Thereby, this female
spline 147a is linked to a male spline 82a formed in the low end
portion of the output shaft 82.
[0070] A ball joint 151 includes a bolt portion 151a provided to
the end portion of the ball joint 151 that is attached to the rear
portion of the center arm 147 with a nut 152.
[0071] A nut 154 is provided for fixing the center arm 147 to the
output shaft 82 by linking the nut 154 to a male screw provided to
the extremity of the output shaft 82.
[0072] The foregoing downward projecting portion 141a of the axle
supporting member 141 and the center arm 147 constitute a lower
handlebar stopper 156.
[0073] FIG. 3 is a front view of a main part of the vehicle
according to the present invention. FIG. 3 shows that the housing
101 is attached to the electrically-operated power steering unit 24
with the plurality of bolts 103, and that the housing 101 covers
the top of the electrically-operated power steering unit 24.
[0074] The housing 101 covering the top of the
electrically-operated power steering unit 24 in this manner makes
it possible to protect the electrically-operated power steering
unit 24 from flying gravel, rain water, dust and the like.
[0075] FIG. 4 is a plane view of the main part of the vehicle
according to the present invention. FIG. 4 shows that the upper
section of the housing 101 and the L-shaped projecting portion 86c
of the lower shaft 86 constitutes an upper handlebar stopper 161
for restricting the range in which the handlebar 37 rotates.
[0076] FIG. 5 is a plane view of the housing according to the
present invention. With regard to the housing 101, sideward
projecting portions 101b and 101c are integrally formed with each
other. The sideward projecting portions 101b and 101c projects
sideward outside the hole section 101a, which is provided to the
upper section of the housing 101, in the vehicle-width direction
(in the upward and downward directions of FIG. 5). A reception
surface 101d is provided to each of these sideward projecting
portions 101b and 101c. The reception surface 101d is capable of
abutting on the L-shaped projecting portion 86c (see FIG. 4) of the
lower shaft 86 (see FIG. 4). In addition, a bolt inserting hole
101f is provided in the housing 101 for the purpose of causing the
bolt 103 (see FIG. 3) to be inserted into the bolt inserting hole
101f.
[0077] The reception surface 101d is a part obtained by cutting the
surface of the raw material in order to accurately restrict the
angle at which the handlebar 37 (see FIG. 1) rotates.
[0078] FIG. 6 is a diagram showing the housing 101 of FIG. 5 in a
direction indicated by an arrow 6. FIG. 6 shows that an opening
101j is made in a part at the right of the center of a rear wall
101h of the housing 101, and that the reception surfaces 101d and
101d which are plane are formed on the left side and the right side
of the upper section of the housing 101.
[0079] A conductor 158 (see FIG. 2), for the power supply connected
to the electrically-operated power steering unit 24 (see FIG. 2),
and for the control of the electrically-operated power steering
unit 24, passes through the opening 101j.
[0080] Descriptions will be provided next for an operation of the
foregoing upper handlebar stopper 161.
[0081] FIG. 7 is an operational diagram showing the operation of
the upper handlebar stopper according to the present invention.
[0082] When the lower shaft 86 rotates in response to the rotation
of the upper shaft 85 (see FIG. 2), end surfaces 86h and 86j of the
L-shaped projecting portion 86c provided to the lower shaft 86
respectively hit the reception surface 101d and 101d of the housing
101. Thereby, the range in which the lower shaft 86 rotates is
restricted. A position of the L-shaped projecting portion 86c which
is shown by a solid line in the figure is that which is observed
when the handlebar 37 (see FIG. 1) is located at a position for
causing the vehicle to operate in a forward direction. A position
of the L-shaped projecting portion 86c which is shown by an
imaginary line in the figure is that which is observed when the
range in which the lower shaft 86 rotates is restricted.
[0083] .theta. denotes a range in which the lower shaft 86 rotates
clockwise and counter-clockwise from the position wherein the
handlebar is located for causing the vehicle to operate in a
forward direction. Concurrently, .theta. denotes ranges in which
the handlebar 37 and the upper shaft 85 rotate respectively.
[0084] Descriptions will be provided next for an operation of the
lower handlebar stopper 156.
[0085] FIG. 8 is an operational diagram showing the operation of
the lower handlebar stopper according to the present invention.
[0086] Tie rods 165 and 166 move in the vehicle-width direction in
response to rotation of the output shaft 82, and the right and left
front wheels 18 and 18 (see FIG. 1) are accordingly steered. The
tie rods 165 and 166 are linked respectively to tie rod linkage
parts 147c and 147d provided to the rear section of the center arm
147.
[0087] The rotational range is restricted by sideward projecting
portions 147f and 147g, more specifically abutting surfaces 147i
and 147k, which are provided to the two sides of the center arm
147, hitting the downward projecting portion 141a, more
specifically reception surfaces 141c and 141d, of the axle
supporting member 141 (see FIG. 2), when the center arm 147 rotates
in response to the rotation of the output shaft 82.
[0088] A position of the center arm 147 which is shown by a solid
line in the figure is that which is observed when the handlebar 37
(see FIG. 1) is located at a position for causing the vehicle to
operate in a forward direction. A position of the arm center 147
which is shown by an imaginary line in the figure is that which is
observed when the rotation of the handlebar 37 is restricted as a
result of turning the handlebar 37 to a large extent.
[0089] .theta. denotes a range of an angle at which the center arm
147 swings clockwise and counter-clockwise from the position at
which the handlebar is located while the vehicle is operated in a
forward direction. Concurrently, .theta. denotes a range of an
angle at which the output shaft 82 rotates. .theta. is larger
than.theta. which has been shown in FIG. 7, and which denotes the
range of an angle at which the lower shaft 86 rotates. In other
words, the upper handlebar stopper 161 starts to operate before the
lower handlebar stopper 156 operates. To put another way, the range
of the angle at which the upper handlebar stopper 161 rotates
starts to be restricted before the range of the angle at which the
lower handlebar stopper 156 rotates is restricted.
[0090] Descriptions will be continued by referring to FIG. 1 again.
The rough terrain vehicle 10 includes an overturn sensor, which is
not illustrated. In a case where the rough terrain vehicle 10 turns
over, the sensor stops the supply of fuel to the engine and the
supply of power to the electrically-operated power steering unit
24.
[0091] Thereby, the electric motor is not operated even if a torque
is detected from the handlebar 37 or the front wheels. Thus, an
assist power is not generated. Accordingly, no load is imposed on
the torque sensor unit. In addition, power consumption from the
battery is held in check.
[0092] As shown in FIG. 2, a first aspect of the present invention
is the rough terrain vehicle 10 (see FIG. 1) in which the steering
shaft 38 is rotatably supported by the upper section of the vehicle
body frame 11, the handlebar 37 (see FIG. 1) is attached to the
upper end of this steering shaft 38, the input shaft 81 provided to
the electrically-operated power steering unit 24 is linked to the
lower end portion of the steering shaft 38, and the output shaft 82
provided to the electrically-operated power steering unit 24 is
rotatably supported by the lower section of the vehicle body frame
11. The rough terrain vehicle includes the gear case 102 included
in the electrically-operated power steering unit 24 that is
attached to the lower section of the vehicle body frame 11. The
lower end portion of the steering shaft 38 is rotatably supported
by the housing 101 annexed to the gear case 102 in the form of a
tower with the upper bearing 107 as a bearing interposed in
between.
[0093] By this, both of the input shaft 81 and the output shaft 82
of the electrically-operated power steering unit 24 are supported
by the lower section of the vehicle body frame 11. Consequently, in
the case where the electrically-operated power steering unit 24 is
supported by the vehicle body frame 11, this support makes the
electrically-operated power steering unit 24 less likely to be
susceptible to the influence of an inaccuracy in manufacturing the
vehicle body frame 11, a change in the shape thereof and the
like.
[0094] A second aspect of the present invention, as shown in FIG. 2
and 7, includes the lower section of the steering shaft 38 being
provided with the upper handlebar stopper 161 for limiting the
angle at which this steering shaft 38 rotates to the predetermined
angle .theta., and that a part of the steering shaft 38 in a the
vicinity of this upper handlebar stopper 161 is attached to the
housing 101 with the upper bearing 107 interposed in between.
[0095] This makes it possible for the upper handlebar stopper 161,
for example, to prevent the torsion bar 126 for detecting the
steering torque from being twisted at an angle larger than the
predetermined angle, the torsion bar 126 being included in the
electrically-operated power steering unit 24.
[0096] Moreover, the part of the steering shaft 38 in the vicinity
of the upper handlebar stopper 161, more specifically, the lower
shaft 86, is attached to the housing 101 with the upper bearing 107
interposed in between. This makes it possible to receive a torque,
which is produced when the upper handlebar stopper 161 operates, by
use of a rigid bearing supporting part, more specifically, the
upper section of the housing 101 which supports the middle-section
bearing unit 104.
[0097] A third aspect of the present invention, as shown in FIG. 2,
includes the lower end portion of the steering shaft 38, more
specifically, the lower shaft 86 and the input shaft 81 are linked
to each other, and that the steering shaft 38 and the input shaft
81 are configured to be capable of being displaced relative to each
other in the axial direction.
[0098] This makes it possible to make a thrust force less likely to
work on the input shaft 81, and to accordingly protect the
electrically-operated power steering unit 24, when an external
force works on the steering shaft 38 because of inaccuracy in
manufacturing, and assemblage into, the vehicle body frame 11 as
well as change in shape of the vehicle body frame 11.
[0099] A fourth aspect of the present invention includes the upper
bearing 107 being configured to be of a double-row type.
[0100] This makes it possible to enlarge the bearing load which the
upper bearing 107 is capable of supporting, and to accordingly
enhance the reliability.
[0101] A fifth aspect of the present invention includes the
steering shaft 38 that is divided into separate units which are the
upper shaft 85 near the handlebar 37 and the lower shaft 86
including the upper handlebar stopper 161. One linkage portion
where the upper shaft 85 and the lower shaft 86 are linked to each
other is formed in the shape of a shaft. The other linkage portion
where the upper shaft 85 and the lower shaft 86 are linked to each
other is formed in the shape of a hole, and concurrently the
expanding slot 85b is provided in the interstice between the outer
circumferential surface of this linkage portion and the inner
circumferential surface of the hole. In addition; one of the
linkage portions is fitted into the other of the linkage portions
above the upper bearing 107, and the linkage portions are fastened
to each other.
[0102] This makes it possible to easily and securely link the upper
shaft 85 and the lower shaft 86 to each other.
[0103] A sixth aspect of the present invention includes forming the
positioning portion 86B of the upper bearing 107 and the
positioning portion 86A of the upper shaft 85 in the lower shaft
86.
[0104] Thereby, for example, the upper bearing 107 is positioned in
the housing 101, the lower shaft 86 is positioned in the upper
bearing 107, and the upper shaft 85 is positioned in the lower
shaft 86. In this manner, the assemblage can be carried out
efficiently.
[0105] A seventh aspect of the present invention includes the lower
handlebar stopper 156 as the second handlebar stopper that is
provided to the lower section of the electrically-operated power
steering unit 24, and that, when rightward and leftward steering is
performed with the handlebar 37 (see FIG. 1), the upper handlebar
stopper 161 starts to operate before the lower handlebar stopper
156 operates.
[0106] In the case where the electrically-operated power steering
unit 24 is provided with the torsion bar 126 for detecting the
steering torque, this makes it possible to prevent a large load
from working on the torsion bar 126 while the handlebar 37 is being
operated.
[0107] An eighth aspect of the present invention, as shown in FIGS.
2 and 6, the opening 101j is provided to the rear wall 101h as the
rear surface of the housing 101, and that the conductor 158 to be
connected to the electrically-operated power steering unit 24 is
configured to pass through the opening 101j.
[0108] This makes it possible to make flying gravel, rain water,
dust and the like less likely to enter the housing 101 from the
front of the vehicle. In addition, the configuring of the conductor
158 to pass through the opening 101j makes it possible to manage
the conductor 158 easily, the conductor 158 being connected to the
electrically-operated power steering unit 24.
[0109] In the case of this embodiment, with regard to the steering
shaft 38, the upper shaft 85 and the lower shaft 86 are linked to
each other with the serration, and the lower shaft 86 and the input
shaft 81 are linked to each other with the serration, as shown in
FIG. 2. It should be noted, however, that their linkages are not
limited to this example, and that the two pairs of shafts may be
linked to each other with splines or other types of means (for
example, joints).
[0110] The steering shaft supporting structure according to the
present invention is suitable for vehicles each equipped with the
electrically-operated power steering unit.
[0111] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *